Hormonal biochemical evaluations are conducted of unmedicated patients suffering major depressive disorders. 24 hour patterns of cortisol and prolactin, and nocturnal patterns of HGH secretion are measured, as is the cortisol response to dexamethasone. The HGH and cortisol response to intravenous dextroamphetamine, and the HGH and prolactin response to hypoglycema are assessed in morning and evening in depressed and normal subjects. The TSH response to TRH, and the diurnal excretion of urinary MHPG are also measured. Correlation are sought among the hormonal abnormalities, with diurnal urinary MHPG excretion, and with clinical features of the illness. A modified neuroendocrine and biochemical assessment is also conducted of children with major depression. The prolactin responses to haloperidol therapy, and to dopamine agonists (dopamine and apomorphine) are being assessed schizophrenic patients. Correlates with plasma haloperidol level and clinical response are sought.